Once all of the search criteria are filled out in the Search options menu, please click the "Search" button at the bottom of the screen:
This action launches the search, and it gets saved into the History as a new search
(each time you go back into the search menu, adjust the parameters, and click the search button like that, the system treats it as a completely new search)
However, if instead you click on Set search options, you will see the alternative features:
Overwrite and launch will update the current search parameters, and restart the search without creating an additional item in history. Please keep in mind that you will need to restart your work on the search - your applied attributes (comments, colors, selections) are not saved in this case. It is indeed a completely new search, but this option keeps your history organized without creating duplicative entries.
Save params into history can be useful for cases when you are building a complex query and there is a need to save the criteria without launching the search (you can later find this search parameteres in History and launch when ready to work on it)
Copy option makes an exact copy of your current search with a new search ID that saves all components of the original search